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One of the primary roles of maintenance and reliability professionals is to run their plant profitably at peak capacity while operating safely and efficiently. As plant professionals strive for increases in production, few would put lubrication at the top of their list of ways to increase plant performance. However, failing to identify the optimal lubricant for an application can lead to decreased efficiency, increased maintenance and the most menacing word of all, “downtime.”

There are roughly 26,000 applications for lubricants in the United States, and each application requires specific performance from its lubricant. Base Oil (mineral versus synthetic), viscosity, additive package, oxidation resistance and thermal stability, are just a few of the characteristics that must be considered when choosing a lubricant.

Identifying the correct lubricant can be a daunting task, especially when faced with all of the other dynamics that impact plant performance. Our own maintenance and reliability staff handles these same issues at the Shell Houston Lubricant Plant, which runs 13 production lines for packaging. The plant can process quart and gallon bottles, pails and drums simultaneously. At a rate of 18,000 quarts per hour, each line is integral to our lubricants business. Letting those lines go down for just a single hour can have a significant impact on production, greatly affecting our customers.

No matter how well developed a production plan is, problems will inevitably arise. The best companies are the ones that can prevent minor problems from developing into very expensive ones. Knowing how efficiency affects our business helps us understand yours. As a result, we work hard to align our entire business around delivering growth and quality customer support.

Your success is our successAt Shell, we believe our success comes from helping our customers succeed, so we work closely with them to develop insight into their businesses. We ensure that we have an intimate understanding of their challenges and goals. Once that foundation has been created, our team begins a customer “deep dive” to identify the customer’s particular needs.

Some of our customers have very intense requirements—onsite maintenance, technical service, new technologies, research and development, the whole package. Companies with multiple facilities often have very specific needs and depend upon 24-hour-a-day reliable service. As downtime can potentially lead to lost revenue, it is important for reliability professionals to identify the lubricants that meet the demands of their machinery and help keep them running efficiently.

Regardless of plant size, maintenance and reliability professionals should take advantage of the services lubricants companies can provide. As facilities are pressured to perform more efficiently with fewer resources, it is beneficial to employ experts who can help you make the most informed lubricant decisions. By reviewing plant equipment applications and operating conditions, suppliers can develop customized lubrication programs that help your facilities work more efficiently.

A lubricants company can provide diverse resources that are not always at hand for most maintenance professionals. For instance, fiber optic video inspection can often save plants time and money by inspecting internal components without dismantling the equipment itself. Some suppliers can also do in-depth fluid and equipment analysis to alert them to conditions that lead to premature equipment failure.

Ultimately, selecting the right lubricants and applying them correctly can have a big impact on your plant’s productivity and total operations cost. World-class lubricants companies are capable of delivering value-added services that support maintenance and reliability professionals in their efforts to deliver superior results. Make the most of your lubricants supplier relationship by asking what they can do to help optimize your business. MT

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Fundamental to success in any organization is getting individuals to work toward common goals. Whether that’s a team of five on the court or a corporation of 50,000 associates scattered across the globe, knowing the goal and working toward unified objectives help every individual contribute. In global manufacturing, however, we frequently see a disconnect in this unified approach.

As global economic trends lead to changes in manufacturing strategies, companies today are realizing that successful financial performance can only be achieved when functional decisions are synchronized and fully aligned with plant or corporate goals and objectives. In rethinking the value and contribution of the manufacturing organization, companies have an opportunity to revitalize their business performance and bring new capabilities to their strategic focus.

A historical disconnectThe front office traditionally has had little direct infl uence on the plant fl oor beyond providing budgets and productivity demands. Conversely, the plant fl oor has little executive visibility, meaning manufacturing considerations are less likely to be taken into account when corporate managers are setting business objectives. In the rare instances when these overarching objectives are communicated to those responsible for the plant fl oor, it’s difficult to reconcile them with plant fl oor deliverables, as the corporate terminology and plant floor metrics rarely converge. This leaves plant managers to set goals and make decisions that risk running counter to the company’s overall objectives as they strive to reach productivity metrics.

The renewed emphasis on effective capital asset management is putting increased pressure on plant managers to contribute to the growth and financial performance of their organizations. The touted benefits of individual initiatives, such as process efficiency and improved quality, mean little if they fail to help plant fl oor personnel understand how they can help address the fundamental corporate goals.

One difference between organizations that succeed and those that fail has to do with the way the manufacturing function is structured, the responsibilities and tactical vision of the plant manager, and the level of integration between plant fl oor decision making and the strategic direction of the enterprise as a whole.

Clearing the hurdlesOne of the main obstacles to strategic alignment is the modern global enterprise itself, which is comprised of multiple facilities and widely dispersed geographic locations. On the plant fl oor, localized tactical deployments and siloed functions have led to unique, dedicated systems for manufacturing planning, execution, process control and tracking, oftentimes for each plant. Consequently, the plant fl oor has become the sole focus of the plant manager, where decisions are made primarily to meet production deadlines and efficiencies, rather than with a more holistic view of company objectives.

Central control through large functional departments also can act as a barrier to strategic execution. Executives typically develop strategy at the top and implement it through a centralized command-and-control culture. This system was acceptable 40 to 50 years ago when change was incremental, but is inadequate in today’s dynamic business environment. Rapid changes in technology, competition and regulations mean that strategy development and implementation has to be a continual and participative process.

Coordinated metric development is another fundamental challenge to strategic alignment. For instance, in many companies, there is no visibility to the losses incurred from unnecessary downtime or late deliveries, and no tangible returns attached to manufacturing’s role in meeting quality standards or making on-time deliveries. Consequently, many companies grossly underestimate the overall effect plant fl oor decisions have on the company’s bottom line.

Communications is another hurdle. Organizations today need a language for communicating strategy as well as processes and systems to implement strategy and gain feedback about it. If the strategy does not get translated through the organization to each individual person, then successful execution is at risk. Ultimately, people must have a “line of sight” between their role and the objectives and implementation of the strategy.

Integration at all levelsMuch of the progress companies have made toward strategic alignment has been simply the result of better information integration across the enterprise. Tremendous operational efficiencies have been gained by connecting “islands of factories” together into a single integrated manufacturing enterprise. This allows companies to drive operational excellence across and beyond the entire enterprise, including business processes, supply chains and customer networks.

For example, planning long-term shutdowns for capital repairs needs long-term visibility into sales and operations planning. Likewise, the factory supply chain needs to consider and integrate the maintenance function in order to be responsive and proactive. This requires rethinking the way plant fl oor functions are executed, as well as providing support through integrated systems that unify data protocol across plant-wide systems and processes and into executive suites.

This seamless information sharing results in knowledge that improves performance and meets core business objectives. If the plant fl oor understands, for example, that on-time delivery is more important to helping reach corporate customer-satisfaction goals than cost savings, it can add a second shift to help meet those on-time delivery goals.

While most plant fl oor decisions are grounded in the same fundamental vision as the rest of the company, the manufacturing function often operates with different priorities and different reward systems than the rest of the organization. Achieving strategic alignment requires every organizational function to be working toward the same goals. This means strategy must be communicated and then aligned with the personal objectives of individuals throughout the organization—not just at the corporate level.

Just as corporate managers often don’t see eye-toeye with plant managers, the reverse is also true. When communicating the value that manufacturing provides, plant managers need to link results back to the metrics that drive the company’s business, demonstrating how these pertain to management goals and customer demands. For example, how will installing a new condition monitoring system help improve equipment uptime and reduce expenses related to lost production and scrap? More specifically, how does this impact the priceper- product ratio—an underlying management goal? Another example is the incompatibility of purchasing metrics with overall plant management’s capital spending goals. There are instances when purchasing’s focus on lower prices may lead to decisions based on unit cost rather than total installed cost of the system or long-term maintainability.

Naturally, each group pursues business objectives from different perspectives. In many cases, distinct differences in language and methods of communication lead to misinterpretations and a general lack of understanding between the top fl oor and the shop fl oor. Therefore, it’s important that organizations translate the strategy into operational terms.

For example, most companies hinge their success on a simple principle: deliver high quality products at affordable prices. To meet this goal, every facet and supporting element of a company’s manufacturing process needs to be as lean as possible.

By leveraging a plant fl oor strategy that focuses on reducing expenses, improving uptime and optimizing production processes, the company can parlay this philosophy into higher profits in the long-term while gaining a distinct competitive advantage. Without a cohesive understanding of these objectives, however, support personnel might take a short-term view of this approach and cut costs wherever possible, sacrificing the long-term goal for short-term gains. For example, the condition monitoring system mentioned before may provide significant long-term productivity benefits to the factory, but budgetary constraints and performance metrics driven through the purchasing department may lead to a more traditional system. The unit cost would be less but the ongoing benefits would be lost.

In other organizations, the value brought by the plant fl oor may be measured by how it impacts production throughput. Here, the equation is simple: if machines aren’t available, the company can’t produce products and profit opportunities are missed. In this scenario, the entire manufacturing organization takes equal responsibility for uptime, quality and profitability. The goal is to make a certain number of units per day, based on market demand, and do whatever it takes to get it done.

In this situation, the priority of plant fl oor personnel isn’t on preventive activities, but rather on directly supporting production output goals. But, if a plant manager is not briefed on the strategic objectives of the company and how they apply to him, he or she may approach the repair intent on getting the plant up and running as cheaply as possible. If a plant manager knows the company objective involves a long-term approach to productivity and profitability, all the options may be reviewed in order to find the one that meshes best with the company’s goals.

Measurement is keyFinding a way to measure improvements is an important step toward achieving strategic alignment. Every organization measures success by some metric, whether it’s price per unit, earnings per share or total sales. Unfortunately, the metrics used in the front office aren’t always easily converted into day-to-day tactics employed on the plant fl oor or in other internal departments, like marketing or accounting.

Despite changes in the speed of business and the availability of information, the methods for evaluating corporate performance remain largely unchanged. The problem with many of these tools is they offer a siloed approach and fail to capture many of the interdependencies among functional areas and link them to wider business goals.

A multi-dimensional view is necessary because any one performance measure can be managed to the detriment of other measures (i.e., the benefits of reduced inventory can be offset by an increase in overtime and expediting costs). Consequently, it’s imperative that measurements be based on the priorities of the strategic plan and that they provide data about key processes, outputs and results.

The measures should be selected to best represent the factors that lead to improved customer, operational and financial performance. For example, most plant managers are concerned primarily with short-term budgets and productivity. A company that includes sustainability as part of its strategic objective, though, needs to brief its plant manager(s) on that goal so they take these elements into account. Such an approach might encourage investing in energy-efficient drives to reach sustainability metrics.

One technique that has proven effective in helping companies align their business and plant-level strategy is the development of cross-functional scorecards, sometimes referred to as “Balanced Scorecard.” Used for more than a decade as a strategic planning and management system for driving accountability for execution, the Balanced Scorecard creates a system of linked objectives, measures and targets, which collectively describe the strategy of an organization and how that strategy can be achieved. Individual departments can retain their individual priorities yet know their contribution and role in the overall strategic framework.

One advantage of the Balanced Scorecard approach is that it provides a framework that adds strategic non-financial performance measures to traditional financial metrics to give managers a more “balanced” view of organizational performance. To provide detailed strategy at the corporate as well as plant level, companies can build scorecards for all business units and key support functions. When implemented successfully, it offers a truly bottom-up approach, supplying managers with feedback around both the internal business processes and external outcomes in order to continuously improve strategic performance and results.

Widening the accountabilityNothing kills a strategy faster than under-committing resources. Thus, it’s critical that managers understand the financial commitments that are required to implement a plan and provide the necessary support once the plan is approved. While there are no easy choices or silver bullets here, the foundation for strategic alignment is one that takes a disciplined approach, includes well-defined, balanced objectives and drives accountability and transparency for the decisions and actions that are made.

With today’s advances in technology, companies now can fine-tune almost every phase of production for maximum yield, quality and profit. Still, technology is only part of the equation. The ability to align business strategy across the organization is the missing link. While a unified business strategy isn’t going to solve every problem, it does widen the accountability for financial performance from the top fl oor to the plant fl oor. This is one trend that most certainly will pay dividends in today’s highly competitive manufacturing market. MT

Bob Ruff is senior vice president of Control Products & Solutions, Rockwell Automation.

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Corrosion is always on the prowl, ready to take down your equipment, fixed and otherwise. Don’t let this predator catch you off guard.

Metallic corrosion is a naturally occurring process that takes place at varying rates—depending on the specific combination of alloy and application conditions— unless there is intentional intervention to modify the situation. Corrosion is an inherent force like gravity. The laws of thermodynamics dictate that corrosion will occur in many situations. Principles of electrochemical kinetics define the rates at which those possible processes occur.

Among the many possible failure modes for physical assets in manufacturing operations, corrosion is one that has major economic impact. While this is primarily true for fixed equipment, corrosive attack also can cause or contribute to failures in rotating equipment.

Although corrosion analysis and control closely depends on knowledge of metallurgy, that is just one starting point. Frequently, the effective choice and use of the alternative corrosion-control methods also draws on knowledge from the fields of chemistry and mechanical and electrical engineering. Complicating things is the fact that corrosion comes in several distinct forms (see Table I).

Rational decision-making regarding corrosion control is best done when the total life-cycle cost of each alternative is clearly defined. Often, the values of future costs and their timing depend on best-available estimates. Then, the financial techniques of discounted cash flow analysis should be applied. Hopefully, it is now well known that considering initial cost as the only criterion for choosing among corrosion-control measures for long-term use makes no practical sense. This is especially true when the cost of lost production during an unplanned shutdown as a result of corrosion failure is massive relative to the initial costs of each alternative. The details of this aspect of corrosion- control decisions are not considered here, but such analyses are essential. The four primary areas of corrosion control are:

Material selection

Coatings

Cathodic Protection

Chemical Inhibitors

In addition, there are several specific actions that can be applied in particular circumstances to help with corrosion problems. (Some of these are listed with brief comments at the end of this article.)

The recommended way to start this decision process is to first evaluate what the most probable form(s) of failure are likely to be—either due to corrosion or something else. The better we initially can estimate what failure mode is most probable, the better we can make provisions to stop or minimize its effects in service. For example, if the given equipment is known to require a high resistance to wear to prevent loss of function in the application, but there also is a possibility of corrosion, addressing the more pressing wear issue will take priority. In another case, one form of corrosion may be much more likely than the others. Thus, attention to that form of attack is emphasized first—but without ignoring the other possibilities.

Clearly, there are many ways to address the problem of in-service equipment failures. When it comes to corrosion- control methods, there are numerous options to review. Awareness of the major alternatives is an important first step.

Material selectionThe control method here is based on the inherent levels of corrosion resistance of the candidate alloys in the given environmental conditions.

To make the materials choice, the decision maker must attempt to know—to the greatest extent possible—the general chemical make-up and/or the concentration of the corrosive medium, as well as other variables important to corrosion. The latter may include the presence and concentrations of trace elements in the general medium, e.g., chloride ions or oxygen or other oxidizing components such as cupric or ferric ions, the maximum operating temperature, the flow velocities, the level of both applied and unavoidable residual stresses and whether the applied stresses are static or cyclic. The possibilities of “worse case” variations in operating conditions due to process upsets and start-up and shutdown periods must also be considered. Other factors include how long the selected material must provide useful service and whether periodic preventative maintenance monitoring can or will be done over time.

Examples of good versus poor material selections are reflected in the following:

Good…

Mild steel for an above-ground storage tank (AST) for very concentrated sulfuric acid at ambient temperature

Type 316L stainless steel instead of Type 304L for a welded nitric acid tank (the molybdenum in the 316L degrades its resistance in strongly oxidizing acids such as nitric)

CoatingsMost coatings—but not all—function primarily by providing a barrier between the corrosive medium and the substrate metal below. This category of corrosion control is the most widely used.

There are several different types of coatings, e.g., organic and inorganic paints and primers, galvanized coatings on steel and anodization on aluminum alloys. The many varieties of paints and primers get the most widespread use. Among these three examples, only galvanized steel provides corrosion control primarily by the process of sacrifi- cial anode, cathodic protection (CP). CP is described below.

Many coating specialists advocate a systems approach for the use of paints and primers. This means the finished protective coating is considered as a synergistic whole where each part has an important but separate role in achieving success. Generally, a good system will consist of clear specifications, excellent preparation of the substrate surface, application of a primer, application of a top coat and competent field inspection at all stages of the process. It is widely agreed that surface preparation is—by far—the most important factor in achieving success.

It is always wise to spend more and achieve an excellent job of surface preparation, even if the top coat selected may be compromised. A well-prepared substrate is most important because it provides a base for good adhesion of either the primer (if one is used) or the top coat. Adhesion of the coating is critical.

Cathodic protection Aqueous metallic corrosion always involves a flow of electrical current through the corrosive medium (known as the electrolyte) between the anodic portions of the exposed metal surface and the cathodic portions of that surface. The rate of corrosion is directly proportional to the rate of this current flow. The CP method functions by supplying a counteracting external current to greatly lessen the rate of corrosion that would otherwise occur. This external current changes the exposed surface being protected so that it becomes essentially all cathodic where little or no corrosion occurs. The anodic reaction then occurs on nearby installed anodes that supply the counteracting current.

There are two types of CP. One is sacrificial anode (or galvanic) CP, in which the currentsupplying anodes are consumed over a period of years, but in the process the metallic asset is protected. The second type is impressed current cathodic protection (ICCP). Here the anodes are not consumed but they act to transfer DC current to protect the asset. Current is supplied to the anodes from an AC to- DC current rectifier that must be connected to an AC electric power source. Each method has advantages and disadvantages depending on the specific application.

CP is very frequently used in conjunction with a coating. This greatly decreases the amount of current required for protection. Therefore, sacrificial anodes last much longer or the amount of power consumption required in an ICCP system is much less. Federal law commonly requires the use and regular monitoring of coated CP systems for underground metallic pipelines and storage tanks used to handle hazardous fluids.

CP is used most often to protect underground metallic structures from soil corrosion. However, it is also applied to protect external tank bottoms in ASTs, for the water boxes of surface condensers used on large steam turbines and for the steel hulls of marine vessels.

Chemical inhibitors Corrosion inhibitors are organic or inorganic chemicals that are added in small quantities to a corrosive medium so that the rate of corrosion of exposed metal is signifi- cantly reduced. There are many types and they function by several mechanisms. While inhibitors are commonly used in cooling water systems and in boiler feed water to steam boilers, they also are used with acid solutions. Vapor phase inhibitors often are included inside shipping containers for equipment to prevent atmospheric rust during prolonged shipment and storage periods.

Many inhibitors function in liquid systems by precipitating out of solution and forming an insoluble, microscale barrier film on the metal surfaces being protected. Thus, they act by retarding the anodic, the cathodic or (most effectively) both of these corrosion reactions on the metal. Examples of this type are certain alcohols, amines, sulfur compounds and phosphates.

Another class of inhibitors is known as oxidizers or passivators. They function by affecting the cathodic reaction and changing the electrochemical corrosion potential of the exposed metal so that it is in a low corrosion- current region. Traditional examples of this type are chromates and nitrites, but these have environmental problems. An alternative is to use molybdates.

Inhibitors known as oxygen scavengers react with residual oxygen in boiler feed water (after mechanical oxygen separation has been applied) to negate oxygen pitting of steel boiler components. Examples of this type inhibitor are sodium sulfite and hydrazine.

Certain cautions apply in the use of inhibitors. Typically, they are economically feasible (for liquid applications) only in recirculating systems and not for once-through systems. Because there is such a wide range of inhibitors, selection can be complex. The means of injecting the chosen inhibitor and monitoring its concentration throughout the system often is critical. The classic example of the importance of this relates particularly to oxidizing (or passivating) inhibitors. If concentrations of this type are too low within a given system then accelerated corrosion rates above expected rates with zero inhibitor present can occur. It should be clear that expert advice is needed to use inhibitors correctly.

Other corrosion-control actionsIn certain situations one or more of the following approaches can have merit:

Pay attention to design and fabrication details early in the specification process. These may include provisions for complete drainage; avoiding lap joints in plates and not using “skip” or tack welded joints so as to minimize crevice corrosion sites; making sure electrical insulators are in place between all unavoidable dissimilar metal contacts and if dissimilar metals must be in electrical contact, getting a favorable area ratio by making the more noble (cathodic) metal smaller in area versus the area of the active (anodic) metal.

In rotating equipment, pay special attention to factors related to failure by fatigue, e.g., sharp radii, poor surface finish and castings defects. Depending on the given material and conditions, most realworld fatigue has at least some corrosion involved. “Pure” mechanical fatigue only occurs in a nearvacuum environment. Actual plant conditions, e.g., humid air or worse conditions, encourage corrosion fatigue and contribute to shortened equipment life.

Always consider the need for post-weld stress relief heat treatment. Residual weld stresses can promote as much or more SCC than applied stresses in equipment.

Consider the use of polymeric materials where required mechanical properties and maximum service temperatures permit.

Add a corrosion allowance during the design of pressure vessels, i.e., extra plate or head thicknesses in ASME code-built pressure vessels, beyond the thickness needed for strength if only general corrosion is expected. Localized forms of corrosion like pitting and SCC penetrate metal in erratic steps, which likely will preclude the value of this approach.

ConclusionCorrosion—in its several forms—is the cause of much lost revenue due to failures of equipment in many industrial applications. There are many facets to corrosion control and knowledge in several areas is required to effectively fi ght this predator. It is always advisable to obtain objective, competent advice when seeking the optimal choice among available corrosion-control alternatives. The references cited at the end of this article are good sources for additional information. MT

Gerald O. “Jerry” Davis, P.E., is a principal in Davis Materials & Mechanical Engineering, Inc. (DMME), a consulting engineering firm based in Richmond, VA. He holds graduate degrees in both engineering and business and spent a total of 31 years working in mechanical, metallurgical and corrosion engineering functions for several organizations, including the U.S. Air Force, Honeywell and Battelle Memorial Institute. Website: www.dmm-engr.com; telephone: (804) 967-9129; e-mail: dmme@verizon.net

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Where on earth will you find enough skilled labor to keep your plant running or finish your next job? Perhaps you should start looking in your own backyard.

Available labor in the maintenance and reliability arena appears to have hit a critical low— and the situation seems to be growing grimmer by the day! Yet, the pool of 80 million women in the American work force has barely been tapped to help fill the void. These days, industry experts tell us, fewer than 20,000 women actually are “in the trenches turning wrenches.” What’s really the problem here?

Could it be that women don’t want to work in traditionally male-dominated trades? Research tells us that they want the same thing men do from their jobs—good pay, fair treatment, a chance for growth and an opportunity for a better life. The fact is, very few young women are encouraged to explore careers in the skilled trades. High school educators and career tech advisors wrongly assume that “girls” aren’t interested in “those types of jobs.” But, when young women learn the facts about crafts training, especially about the earning potential, they are very interested, indeed. Thus, we need to make sure teachers and advisers have the facts and keep an open mind about nontraditional employment options. Could it be a matter of women not being able to do the work? Archeological research on prehistoric humans indicates that males and females participated equally in chores of daily living, including the construction and maintenance of the family’s shelter. As recently as World War II, women proved they could succeed in all types non-traditional roles, performing every kind of job America had to offer while the men went to battle. It worked then because everyone agreed that in order to win the war, jobs had to get done. Americans successfully united to march to the beat of a patriotic drum. Women were recruited, hired, trained and compensated well for doing what was traditionally referred to as men’s work. They were proud of their work and men were proud of them!

Or, could the problem be that men simply don’t care to have women in the skilled trades? What the vast majority of men working in these areas really care about are safety, quality and doing a job right the first time, every time. That’s what the vast majority of women care about as well. When given the right training, mentoring and opportunity, they, like men, work safely and produce consistently high-quality work. Proper training allows everyone—regardless of gender—to focus on what all people on the job should be focused on: the work!

Today, our nation faces a different kind of threat than that posed by World War II—an economic one. If we don’t tap into a new and robust labor pool, many of our industries and much of our infrastructure will suffer and our economy will continue its downward spiral. The solution lives and breathes in homes across America, but we must stop pointing fingers at one another and unite just as we did more than 60 years ago. Solving the problem lies in the building of partnerships among industry, education, government and communities—and in tapping under-utilized labor pools.

If your operations are desperately seeking skilled labor, prepare for the problem to get worse. It will! Take action now. Recruiting and training women is a short-term, yet powerful solution with lasting benefits. The skilled trades need good people and women need good-paying jobs. Let’s begin looking in our own backyards for a way to end this labor crisis. MT

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If you’ve ever flown anywhere (or plan to in the future), you’ll appreciate the importance of adequate and reliable balancing and testing of this equipment

Modern jetliners rely on air cycle machines to provide air conditioning throughout the passenger cabin. Not only is this provision available on the ground, where outside tarmac temperatures can reach well over 100 F, but also in flight at altitudes reaching over 30,000 feet and temperatures reaching below -30 F. Air cycle machines are a vital component in maintaining a safe and comfortable cabin environment for millions of passengers around the globe. This means big business for OEMs and overhaul facilities worldwide.

The air cycle machines (ACMs) consist of three main components: fan, compressor and turbine. These three components are mated to a single shaft and support by two journal air bearings, with typical operating speeds between 30,000 and 50,000 rpm.

The problemEach rotating component contains an element of unbalance. Unbalance— an uneven weight distribution—is caused by factors in the manufacturing and assembly processes. This unbalance causes vibration that can lead to stress, fatigue, noise and, ultimately, bearing damage during operation. Therefore, ACMs must be carefully balanced and undergo vibration analysis before entering service to ensure long life and reliability.

Balancing Balancing of the ACM components requires a small horizontal balancing machine. The compressor, turbine and fan components are balanced individually using tooling arbors. (Editor’s Note: Schenck’s RS1 soft-bearing balancing machine can accommodate a majority of the ACM components, including the shafts, and provides flexibility for a service facility to balance other smaller components. For larger components with lower tolerances and those using tooling, an HM2 balancing machine is suitable for the balancing tasks.) Service facilities may have specific requirements and ACM models, so balancing solutions must be determined based on individual needs.

Vibration analysisBefore an ACM is entered into service, it has to pass several tests specified by the OEMs for the individual ACM, including pressure tests, break-in tests, performance tests and balance verification tests. During the tests, numerous parameters are recorded and monitored. Some of the tests require vibration analysis for which Schenck also provides testing equipment.

Vibration analysis includes the measurement of housing vibration and shaft excursion. Housing vibration can be measured using accelerometers. Shaft excursion, also called relative shaft vibration, is measured using two non-contacting displacement pickups (Eddy Current Sensors). Displacement sensors must be installed with a slight shaft clearance perpendicular to each other. The sensitivity of the sensors is dependent upon shaft material and shaft dimensions, so this has to be determined for each type of ACM.

OEM manuals require the monitoring of two components of the shaft excursion signal: synchronous vibration, the component related to the running speed of the rotor, and non-synchronous vibration, vibration not related to the running speed. To provide these readings, the vibration measuring unit uses a tracking filter. A reference signal for speed and phase is provided by laser if the shaft end of the inlet fan is accessible. Should the shaft end be inaccessible, the use of a magnetic sensor is possible providing that the shaft material is steel and incorporates a keyway or other trigger feature. Synchronous vibration is caused primarily by the residual unbalance of the rotor or misalignment, where the components are not mounted concentric and perpendicular to the shaft. If the synchronous vibration exceeds a certain limit, the assembly must be trim balanced.

Synchronous vibration readings (amplitude and phase) are taken at different running speeds. From these readings, an “optimization” procedure is used to calculate the correction weights to minimize the vibration for the complete speed range. Corrections are then performed at the shaft ends. Non-synchronous vibration is an indication of bearing instabilities. In this case, vibration that exceeds tolerance requires the unit to be disassembled and checked. MT

Roland Kewitsch is manager of the Vibration Analysis and Condition Monitoring Group at Schenck Trebel Corporation in Deer Park, NY. His experience in the field spans more than 20 years both in Europe and the USA. E-mail: Roland.Kewitsch@schenck-usa.com

Jan Dittmar is senior applications engineer with the Schenck Jet Engine and Aerospace Group in Deer Park, NY. E-mail: Jan.Dittmar@schenck-usa.com

Schenck Trebel Corporation Deer Park, NY, US

Providing Complete Solutions…

Backed by over 100 years of balancing experience, Schenck Trebel provides a complete line of vertical and horizontal balancing machines for the production, maintenance and repair of any rotating component—from a fraction of a gram to over 600,000 lbs. The company offers a range of vibration analysis equipment, including field balancing machines, balancing tooling and condition monitors for precision rotor performance. Schenck’s nationwide Balancing Technology Centers also provide rotor balancing services and various on-site services, including predictive maintenance and on-line condition monitoring services for critical equipment. But, that’s not all.

Schenck’s total support program goes beyond balancing to provide equipment and technical services, balancing certification, on-site and off-site seminars and in-house balancing services. With more than 60,000 machine installations worldwide, Schenck can offer the right solution. For details, visit: www.schenck-usa.com

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Rosemont, IL in April could never be confused with the sunny south. Nor will it ever be classified as a relaxing resort, entertainment hub or exotic portof- call. Nonetheless, despite having made a weeklong pilgrimage to Rosemont around this time for the past five years, I keep coming back for more.

This year, as usual, the huge “buffet” I have grown accustomed to finding in Rosemont did not disappoint. Over time, it has continued to serve up a vast selection of the tastiest, most nutritious items for our times. With many places to visit, the lines were again short and the crowds, representing a cross-section of people from all over North America and the world, were very friendly. Year after year, those of us who join in this pilgrimage spend our time sharing with each other about our interests, our work and the many and varied mysteries in our lives.

No, my annual trip to Rosemont is not a family outing. It’s not recreation. It’s not a vacation. What it is, however, is one of the best work-related venues available to those in our industry. It’s where participants— regardless of company and specific job titles and responsibilities—can get fired up about reliability, get excited about change and get answers to most, if not all, of their maintenance and reliability mysteries. The Maintenance & Reliability Technology Summit (MARTS) event provides so much for so many. This year, as always, it was a true meeting of the minds, focused on improving plant, facility and equipment performance and reliability.

Plenty of offerings This April, I met many people who had been reading my columns for years—and many more who had just begun reading them. They came from a wide variety of industry sectors, including manufacturing industries, power & utilities, petro-chemical processing, mining and production, higher education, facility engineering and more. More than 190 companies were represented, from 36 states, five Canadian provinces and two from outside North America.

The “nutritious buffet” went well beyond the meals to include something for every maintenance and reliability person in attendance:

Come to think of it, MARTS is not just a meeting of the minds; it’s a veritable “one-stop shopping” destination for today’s (and tomorrow’s) maintenance and reliability leaders!

Plenty of take-awaysI met people from many different industries and locations who were looking for something specific, be it in the form of a tools, a strategy or just a new way to help improve their plant or facility performance and reliability. Some were new to our profession, some were old hands. Some of the participants were there with teams of others from their respective companies, dividing up among the sessions to learn about as many answers/solutions as they possibly could in a few short days—answers/solutions that they could take back to their plants and begin sharing with others.

While I wasn’t able to sit in on all of the sessions, I listened to a range of variety of presenters who told of their maintenance and reliability challenges and how they successfully addressed them. I heard from seasoned veterans and leading experts—people who I have followed throughout my own career—as they talked with authority about maintenance and reliability best practices.

Session participants asked some very hard-hitting questions about problems or opportunities back at their workplace—and expected hard-hitting answers. They received invaluable advice. MARTS sessions not only covered the nuts-and-bolts topics, they also covered some of the “soft” side of maintenance and reliability—i.e., people, organizations, training and work methods. Here are just a few of the nuggets I gleaned from MARTS 2008:

Reliability is a common goal for quality, safety, environmental and equipment performance.

Plenty of tools “Tools you can use” is a term that frequently came to mind as I was sitting in the conference sessions. In other words, what all of us were picking up at MARTS were real tools we could take back to our jobs and immediately put to use. Sometimes these “tools” were the ones that could be used to pry some of the old ideas and paradigms out of the rut we often find ourselves in back at work.

The well-prepared exhibitors also provided tools and methods for addressing specific performance issues with modern and not-so-modern, plants and facilities. Smart tools and smart equipment incorporating some of the “smartest” technologies in the marketplace were demonstrated everywhere we looked in the exhibit hall.

An added bonus at this year’s MARTS was the participation of the 2007 North American Maintenance Excellence (NAME) Award winners. Representatives of the two honored plants—Alcoa Mt. Holly, SC, and Baldor Electric/Reliance Dodge, Marion, NC—discussed their “winning ways.” In both cases, these operations had created a “reliability culture” using the proven methods of Total Productive Maintenance (TPM) to achieve best-in-class equipment and process reliability. The “lessons learned” from past NAME Award winners included examples of operational excellence focused on a foundation of health, safety and environmental plans; clear organizational and strategic planning goals; reliability engineering and defect elimination teams; operators involved in routine maintenance; and asset reliability as a shared responsibility between manufacturing and maintenance.

Plenty of satisfaction The part of this two-day conference and the two days of pre- and post-conference workshops that impressed me the most was how “hungry” for knowledge the participants were. As noted previously, I talked with countless attendees who were looking for something specific—something that they could put to work back at their facilities to help make their jobs easier, their plants more reliable and their businesses more competitive. Their gnawing hunger certainly appeared to be satisfied by week’s end!

Thanks to you To all of you who attended and presented at MARTS 2008, I wish to thank you for sharing your insights with me and with each other. Every year at this event, I learn so much about your various challenges—and so much about the effective solutions that you’re implementing to address those challenge. As a contributing editor, your sharing with me is extremely important. It helps me to focus more accurately on the types of issues that confront you day-in and day-out. Everyone who participated (regardless of your role) added great value to this and future MARTS—as well as future issues of this magazine. I am already looking forward to meeting you next year in Rosemont to learn even more from you.

This year’s meeting of the minds may have come to a close, but the tools, the ideas and the insights are no doubt being put to good use by all of you to make your jobs easier and more productive. What you learned at this year’s MARTS (and those of past years) will contribute to your own organization’s performance, reliability profitability and growth, as well as bolster your respective countries’ competitiveness in a difficult global economy.

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Being proactive is what predictive maintenance is all about.

With coal-fired plants generating a substantial percentage of the electricity produced in the United States, it’s vital to ensure their reliability. Keeping such a plant up and running calls for continual monitoring of equipment and maintenance planning. Even the smallest of components have the potential to shut down operations. That’s why infrared thermography (IR) can be such a powerful tool around these facilities.

IR technology Thermal or infrared energy is light that is not visible because its wavelength is too long to be detected by the human eye. It is the part of the electromagnetic spectrum that we perceive as heat. Unlike visible light, in the infrared world, everything with a temperature above absolute zero emits heat. Even very cold objects, including ice cubes, emit infrared. The higher the object’s temperature, the greater the infrared radiation emitted. IR allows technicians to see what their natural eye cannot.

Situation Mirant Mid-Atlantic, LLC is one organization that has recognized the value of IR in its business. The company generates electricity for various localities in the mid- Atlantic region of the U.S. It owns four power plants in the Washington D.C. area and the coal-fired Chalk Point station in Maryland handles a large portion of the electricity generation for the mid-Atlantic assets.

The Chalk Point facility’s maintenance organization is responsible for ensuring that processing equipment performs as required. Infrared cameras now play a big role in condition monitoring and overall predictive maintenance. Before IR, point measurement was the only type of temperature gauge used. There was no way to look at a whole area or piece of equipment and anomalies were not easily identified.

Mirant Mid-Atlantic currently uses FLIR’s ThermaCAM® T400 infrared cameras as part of its PdM efforts. The information obtained with the T400 is furnished to schedulers and planners so they know what equipment to schedule for repair and when. Having this information gives them the necessary lead-time to order parts and schedule maintenance. The camera also helps identify equipment that does not need maintenance. Eliminating properly functioning equipment from the maintenance list saves time and money.

In these power gen operations, coal is transported from storage to the generating facility by conveyor belt. The FLIR cameras are used to identify problems with pulleys, gearbox drives and roller bearings along the conveyor belts. They also are used to find leaking valves, identify blockages of coal going into the boiler and in boiler tubes. The infrared technology and resulting data lets technicians locate and determine the severity of faults and plan their maintenance activities accordingly.

Maintenance technicians cover a lot of ground in surveying equipment in these operations. The T400 is small and lightweight, making it easy for them to get the job done. The large viewing window and lenses that rotate make it possible to capture images when equipment is in difficult-to-reach places.

Real resultsResults of thermographic inspections vary from equipment to equipment, but understanding the impact of even one piece of equipment or component helps illustrate the benefits of this powerful technology in a PdM program.

A study done by Mirant Mid-Atlantic found that by fixing a typical leaking valve, it saved an average of $5700 annually. In 2007, the company identified 187 valves. The cost of an infrared camera and other diagnostic tools is clearly a solid investment when fixing leaking valves. While the problem may have seemed to be a small one, solving it delivered savings of more than a million dollars.

Catastrophic failure of a conveyor belt also could have an enormous impact on production and costs. Although reserve coal for such situations is available, without new coal entering production, these reserves would quickly diminish and cause electric generation downtime. The ability to see problems before they become catastrophic allows Mirant Mid-Atlantic’s maintenance team to plan and schedule repairs as needed, helping save in terms of maintenance expenditures, downtime and lost production. MT

FLIR Systems, Inc. Billerica, MA

About FLIR

FLIR Systems, Inc. designs, manufactures and markets infrared imaging systems worldwide for a variety of thermographic and imaging applications. FLIR’s thermography products are being used in diverse applications, including predictive maintenance, condition monitoring, non-destructive testing, and research and development and manufacturing process control. To learn more, go to www.goinfrared.com

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No joke, it’s getting a lot quieter out there. You, your equipment and your processes have a number of cutting-edge noise attenuation solutions to thank for it.

Uncontrolled noise in process operations is a serious problem. Unresolved issues with noise can lead to health problems, vibration and, in the most extreme cases, equipment damage. All noise attenuation solutions are not created equal, and no one product will be effective in every situation. It is, therefore, important to understand what is creating noise before attempting to fix the problem.

When fluid travels through a conventional singleseated, globe-style valve, a “vena contracta” (point of narrowest flow restriction) develops directly downstream of the narrowest throttling point. At this point the fluid reaches a minimum pressure and maximum velocity that rapidly recovers to a lower pressure than the inlet pressure. When fluid pressure in the valve drops, the fluid velocity rises—this is called the “Bernoulli Principle.” As the velocity of the fluid increases, the noise generated by turbulence in the fluid also increases (see Figs. 1 and 2).

The driving force behind velocity and, accordingly, noise, is the difference between the inlet pressure and outlet pressure, which represent the energy available to generate noise. When this difference is low, the energy contained in the fluid stream will be low and the noise that is generated typically will be low as well. Each noise solution will have a range of pressure drops where the design is most effective.

Noise attenuation solutionsMost globe valve attenuation solutions use cages with a variety of designs available on the market. A typical solution with drilled holes is shown in Fig. 3. (Pressure through a multi-stage valve is shown in Fig. 4.) Different solutions using one of the noise reduction mechanisms listed in the accompanying sidebar—or a combination of such mechanisms— also are available.

Reducing pressure while controlling velocity is a common method for reducing noise, accomplished by dividing a large pressure drop into smaller pressure steps, which will produce far lower velocities at each step. For example, a sudden contraction followed by a sudden expansion can decrease pressure by creating turbulent zones in the fluid flow. The turbulence takes energy out of the fluid in the form of pressure. This is the effect primarily used by orifice plates. Using several orifice plates will create a high overall pressure drop while generating lower velocities than would a single plate designed to create the same pressure drop.

Design solutions, such as small flow passages, also can help reduce noise. Small passages accentuate the friction formed by the passage walls. As the passage grows smaller more pressure is required to force the fluid to flow.

A mutual impingement design also will reduce pressure without adding velocity to the flow. Mutual impingement is created when two flows impact at 180°, forming a highly turbulent zone that dissipates energy.

Sudden turns in the fluid path are another way to cause the pressure in the fluid to drop. The angle of the turn can have a dramatic effect on the energy loss—angles sharper than 90° are difficult to manufacture but are more effective in reducing pressure.

An acoustical attenuation solution can provide a barrier that blocks noise. This can be accomplished in a number of ways, including insulating the pipe and increasing the distance to the noise source.

Careful engineering of the noise solution includes evaluating any existing attenuation. Often thermal pipe insulation can be used in the evaluation of the noise to reduce the predicted noise level without adding cost to the system.

Understanding the Peak Frequency Effect can offer alternative options for decreasing noise levels. Most noise in a control valve produces a range of frequencies that have a bell curve type distribution and a peak frequency—changes in the geometry of the valve design will shift this peak. It is possible to shift this frequency out of the range of human hearing, which lowers the perceived noise and damage to human organs. Shifting the peak higher also reduces the level of noise that will pass through the pipe, which has a naturally low frequency. A common way to raise the peak frequency is to make smaller outlet holes in the noise control device—cutting a hole diameter in half can lower the overall noise level by up to five decibels. This type of solution is available from all major control valve manufacturers as a cage with small holes.

WaveCracker® technology is a patented technology that reduces noise as flow passes through irregularly shaped cross sections. Tests have shown this technology can effectively reduce noise by more than 10 decibels. WaveCracker works by forming an irregular cross section shape. Sound waves reflecting off the walls of the passage have irregular patterns that cause the sound pressure wave to lose intensity as it moves down the passage (see Fig. 5).

One cause of noise could be harmonic vibration—something that occurs when the valve and pipe approach a common frequency. This problem is characterized by a tell-tale “screech,” where a single frequency is pronounced. Because screech occurs when the frequency of the valve and pipe match, it is not easily predicted.

Noise also can worsen due to reflective surfaces that amplify noise coming from a pipe. A single, flat surface near a valve, like a concrete floor, can add three decibels. Two hard, flat surfaces (like a floor and flat ceiling) that are parallel to one another will add more than six decibels. Adding walls, a ceiling and a floor can add 30 to 40 decibels.

Noise predictionCareful noise predictions will prevent most noisy applications. A number of noise prediction techniques exist with varying degrees of accuracy for different applications. Unfortunately, no standard exists that is the most accurate for all possible conditions.

Most manufacturers have proprietary techniques that will produce acceptable prediction under a range of conditions and with equipment the manufacturer is familiar with. When used outside the acceptable range or with other equipment, however, proprietary techniques can be significantly different than actual noise produced.

The IEC committee has developed the IEC standard 60543-8-2 in an effort to provide an accurate standard that can be used to compare products from different manufacturers. Although it’s not perfect, this method does create a clear baseline that can be used to compare equipment from a variety of suppliers. If noise control is critical around your operations, it is important to study all factors, such as flow conditions, valve design, system installation and available noise prediction methods.

Before you buy… Before purchasing expensive noise suppression equipment, you should ask yourself a few important questions:

How much noise attenuation is actually required?

What are the low-cost alternatives to noise attenuation?

And, if noise attenuation devices are necessary, what lower-cost equipment can be specified?

If the predicted sound pressure level (SPL) exceeds 85 or 90 dBA, noise suppression devices should be considered. If the noise is not associated with equipment damage and is located in a remote location away from people, however, higher noise levels may be acceptable. Other possible low-cost alternatives to noise suppression are piping insulation, discharging the valve into a vessel, relocating the noise source outside an enclosed area, reversing the flow direction through the valve and reducing the pressure drop across the valve.

When noise levels are critical, it always will be important to consult a control valve noise expert. In these cases, the expert will need to gather information and data on your specific application. The more information you are able to provide, the higher the expert’s success rate will be. MT

Selecting The Right Noise Attenuation Solution

The Flowserve Tigertooth design is most effective at high pressure drops where it reduces sound pressure levels using the sudden expansion and contraction phenomenon. The design features highly-engineered concentric grooves—or teeth—machined into the face and backside of a series of circular stacked discs that form the seat retainer. Legs separate one disc from another, providing a gap between individual discs, forming flow passages. The passages are self-cleaning, and grow wider as the fluid passes to allow large solids easy passage through the trim.

Flowserve MegaStream technology (like that shown in the cutaway in Fig. 3) employs a heavy-duty drilledhole seat retainer with up to seven stages to lower noise levels. It is one of the most common solutions to control valve noise. Pressure drops are distributed between the throttling point of the plug and seat ring as well as the stages of the retainer. Each stage is designed to take a small pressure drop, avoiding the high velocities present in single-throttling-point trims. Fluid expansion and velocity are controlled by increasing the flow areas of each subsequent stage. Cutting the MegaStream retainer hole size in half will reduce the noise level by up to 7 dBA through frequency shifting effects.

Flowserve Type I Trim reduces noise generated by moderate pressure drops. By changing only a few parts, the noise reducing cage can be added to the standard valve without special plugs or seat rings. Type II Trim adds a skirt-guided, drilled-hole plug to the attenuators used in the Type I design. The Type II design is most effective at reducing noise generated by moderate to high pressure drops. Type III Trim uses the same skirt-guided, drilled-hole plug as the Type II design and adds a heavy-duty drilled-hole cage. The Type III system is most effective at reducing noise generated by higher pressure drops.

Flowserve XStream Trim eliminates noise in moderate to high pressure drops. Using four drilled hole stages and a contoured plug, the XStream provides noise reduction and turndown. Using small holes in each stage for frequency shifting, the XStream produces lower noise levels while attenuating upstream noise.

Multi-Hole Trim uses a cost-effective, skirt-guided plug head with drilled holes and reduces noise generated by moderate pressure drops. This trim also generates less noise than conventional designs by using small holes in the plug skirt to shift the frequency and lower noise. The Flowserve SilentPac Trim design also reduces noise generated by moderate pressure drops. The noise reducing cage can be added to the standard valve without special plugs or seat rings.

Z-Trim combines the benefits of an advanced control valve with the simplicity of a ball valve. It is most effective with low- to medium-pressure drops, and excels at eliminating noise in high-flow services. The simple design reduces noise by passing the fluid through as many as five stages of pressure reduction.

Anti-noise plates can also be installed downstream of a control valve as a simple, cost effective way to reduce control valve noise without making any changes to the valve. Plates provide lower noise by lowering turbulence, providing back pressure to the valve and providing attenuation on noise generated inside the valve. Plates are most effective in low- to medium-pressure drop application.

An all-in-one solution For the most demanding applications, Flowserve’s Valtek Stealth® design combines all of the most effective noise- and pressure-control mechanisms into one product. The Stealth trim is produced by laser cutting circular discs to form fluid passageways and then braising the discs together to form a seat retainer. Three different discs are cut and matched together to form a flow path set. A number of disc sets are then stacked together and the whole assembly is brazed together to form a stack.

Similar to Tiger Tooth, an important mechanism reducing the pressure in Stealth trim is the sudden expansion and contraction phenomenon that takes place as the flow passes over the teeth. The Stealth trim also takes advantage of frequency shifting by providing small outlet holes. Stealth also features WaveCracker technology that provides extra noise attenuation without creating additional pressure drops in the valve. Angled exit flow paths increase the flow capacity of the valve, reduce exit turbulence and lower noise. Other mechanisms at work in the Stealth design are pressure control, velocity control, attenuation, frequency shifting and noise cancellation.